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the biological perspective

2. the biological perspective. Learning Objectives. LO 2.1 What Are the Nervous System, Neurons, and Nerves? LO 2.2 How Neurons Use Neurotransmitters to Communicate LO 2.3 How the Brain and Spinal Cord Interact LO 2.4 Somatic and Autonomic Nervous Systems

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the biological perspective

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  1. 2 the biological perspective

  2. Learning Objectives • LO 2.1 What Are the Nervous System, Neurons, and Nerves? • LO 2.2 How Neurons Use Neurotransmitters to Communicate • LO 2.3 How the Brain and Spinal Cord Interact • LO 2.4 Somatic and Autonomic Nervous Systems • LO 2.5 How Hormones Interact with the Nervous System and Affect Behavior • LO 2.6 Study of the Brain and How It Works • LO 2.7 Structures and Functions of the Bottom Part of the Brain • LO 2.8 Structures that Control Emotion, Learning, Memory, and Motivation • LO 2.9 Parts of Cortex Controlling Senses and Movement • LO 2.10 Parts of Cortex Responsible for Higher Thought • LO 2.11 Differences between the Left and Right Sides of the Brain

  3. Overview of Nervous System LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Nervous System: an extensive network of specialized cells that carry information to and from all parts of the body • Neuroscience: deals with the structure and function of neurons, nerves, and nervous tissue • relationship to behavior and learning

  4. Figure 2.1 An Overview of the Nervous System

  5. Structure of the Neuron LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Parts of a Neuron • dendrites: branch-like structures that receive messages from other neurons • soma: the cell body of the neuron, responsible for maintaining the life of the cell • axon: long, tube-like structure that carries the neural message to other cells

  6. Structure of the Neuron LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Neurons: the basic cell that makes up the nervous system and receives and sends messages within that system

  7. Figure 2.2 The Structure of the NeuronThe electronmicrograph on the left shows myelinated axons.

  8. Other Types of Brain Cells LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Glial cells are grey fatty cells that: • provide support for the neurons to grow on and around • deliver nutrients to neurons • produce myelin to coat axons • http://cdn.psfk.com/wp-content/uploads/2014/10/harvard-neuroscience-mcb80x.png

  9. Other Types of Brain Cells LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Myelin: fatty substances produced by certain glial cells that coat the axons of neurons to insulate, protect, and speed up the neural impulse • clean up waste products and dead neurons

  10. Neurons in the Body LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Nerves: bundles of axons in the body that travel together through the body • neurilemma: Schwann’s membrane-Tunnel through which damaged nerve fibers can repair themselves • This is the reason that a severed finger or toe if sewed back on in time can recover some feeling. • Neurons in the brain and spinal cord don’t have this coating and would be permanently damaged.

  11. Generating the Message: Neural Impulse LO 2.1 What Are the Nervous System, Neurons, and Nerves? • Ions: charged particles • inside neuron: negatively charged • outside neuron: positively charged • Resting potential: the state of the neuron when not firing a neural impulse • Action potential: the release of the neural impulse consisting of a reversal of the electrical charge within the axon • allows positive sodium ions to enter the cell

  12. Generating the Message: Neural Impulse LO 2.1 What Are the Nervous System, Neurons, and Nerves? • All-or-none: a neuron either fires completely or does not fire at all • Return to resting potential

  13. Figure 2.3 The Neural Impulse Action PotentialIn the graph below, voltage readings are shown at a given place on the neuron over a period of 20 or 30 milliseconds(thousandths of a second). At first the cell is resting; it then reaches threshold and an action potential is triggered. After a brief hyperpolarization period, the cell returns to its resting potential.

  14. Figure 2.3 (continued) The Neural Impulse Action PotentialIn the graph below, voltage readings are shown at a given place on the neuron over a period of 20 or 30 milliseconds(thousandths of a second). At first the cell is resting; it then reaches threshold and an action potential is triggered. After a brief hyperpolarization period, the cell returns to its resting potential.

  15. Neuron Communication LO 2.2 How Neurons Use Neurotransmitters to Communicate • Sending the message to other cells • Axon terminals: branches at the end of the axon • synaptic knob: rounded areas on the end of axon terminals

  16. Neuron Communication LO 2.2 How Neurons Use Neurotransmitters to Communicate • Synaptic vesicles: sack-like structures found inside the synaptic knob containing chemicals • Neurotransmitters: chemical found in the synaptic vesicles which, when released, has an effect on the next cell

  17. Neuron Communication LO 2.2 How Neurons Use Neurotransmitters to Communicate • Synapse/synaptic gap: microscopic fluid-filled space between the rounded areas on the end of the axon terminals of one cell and the dendrites or surface of the next cell • Receptor sites: holes in the surface of the dendrites or certain cells of the muscles and glands, which are shaped to fit only certain neurotransmitters

  18. Figure 2.4 The SynapseThe nerve impulse reaches the synaptic knobs, triggering the release of neurotransmitters from the synaptic vesicles. The molecules of neurotransmitter cross the synaptic gap to fit into the receptor sites that fit the shape of the molecule, opening the ion channel and allowing sodium ions to rush in.

  19. Neuron Communication LO 2.2 How Neurons Use Neurotransmitters to Communicate • Neurons must be turned ON and OFF. • excitatory neurotransmitter: neurotransmitter that causes the receiving cell to fire • inhibitory neurotransmitter: neurotransmitter that causes the receiving cell to stop firing

  20. Neuron Communication LO 2.2 How Neurons Use Neurotransmitters to Communicate • Chemical substances can affect neuronal communication. • agonists: mimic or enhance the effects of a neurotransmitter on the receptor sites of the next cell, increasing or decreasing the activity of that cell • antagonists: block or reduce a cell’s response to the action of other chemicals or neurotransmitters

  21. Cleaning up the Synapse LO 2.2 How Neurons Use Neurotransmitters to Communicate • Reuptake: process by which neurotransmitters are taken back into the synaptic vesicles • Enzyme: a complex protein that is manufactured by cells • One type specifically breaks up acetylcholine because muscle activity needs to happen rapidly; reuptake would be too slow.

  22. Central Nervous System LO 2.3 How the Brain and Spinal Cord Interact • Central nervous system (CNS): part of the nervous system consisting of the brain and spinal cord • spinal cord: a long bundle of neurons that carries messages to and from the body to the brain that is responsible for very fast, lifesaving reflexes

  23. The Reflex Arc: Three Types of Neurons LO 2.3 How the Brain and Spinal Cord Interact • Sensory neuron: a neuron that carries information from the senses to the central nervous system • also called an afferent neuron • Motor neuron: a neuron that carries messages from the central nervous system to the muscles of the body • also called an efferent neuron

  24. The Reflex Arc: Three Types of Neurons LO 2.3 How the Brain and Spinal Cord Interact • Interneuron: a neuron found in the center of the spinal cord that receives information from the sensory neurons and sends commands to the muscles through the motor neurons • Interneurons also make up the bulk of the neurons in the brain. These three neurons help make up the reflex arc- a fast reaction controlled in the spinal cord

  25. The Reflex Arc: Three Types of Neurons LO 2.3 How the Brain and Spinal Cord Interact • Damage to the CNS was once thought to be permanent • We have learned that some forms of CNS damage can be repaired. This is called Neuroplasticity, the ability to constantly change both the structure and function of the cell involved in trauma

  26. Figure 2.6 The Spinal Cord ReflexThe pain from the burning heat of the candle flame stimulates the afferent nerve fibers, which carry the message up to the interneurons in the middle of the spinal cord. The interneurons then send a message out by means of the efferent nerve fibers, causing the hand to jerk away from the flame.

  27. Peripheral Nervous System LO 2.4 Somatic and Autonomic Nervous Systems • Peripheral nervous system (PNS): all nerves and neurons that are not contained in the brain and spinal cord but that run through the body itself • divided into the: • somatic nervous system • autonomic nervous system

  28. Figure 2.7 The Peripheral Nervous System

  29. Somatic Nervous System LO 2.4 Somatic and Autonomic Nervous Systems • Soma = “body” • Somatic nervous system: division of the PNS consisting of nerves that carry information from the senses to the CNS and from the CNS to the voluntary muscles of the body • sensory pathway: nerves coming from the sensory organs to the CNS consisting of sensory neurons

  30. Somatic Nervous System LO 2.4 Somatic and Autonomic Nervous Systems • Somatic Nervous System (cont’d) • motor pathway: nerves coming from the CNS to the voluntary muscles, consisting of motor neurons

  31. Autonomic Nervous System LO 2.4 Somatic and Autonomic Nervous Systems • Autonomic Nervous System (ANS) • division of the PNS consisting of nerves that control all of the involuntary muscles, organs, and glands; sensory pathway nerves coming from the sensory organs to the CNS consisting of sensory neurons • sympathetic division (fight-or-flight system): part of the ANS that is responsible for reacting to stressful events and bodily arousal

  32. Autonomic Nervous System LO 2.4 Somatic and Autonomic Nervous Systems • Autonomic Nervous System (ANS) (cont’d) • parasympathetic division: part of the ANS that restores the body to normal functioning after arousal and is responsible for the day-to-day functioning of the organs and glands

  33. Fight or Flight

  34. Figure 2.8 Functions of the Parasympathetic and Sympathetic Divisions of the Nervous System

  35. The Endocrine Glands LO 2.5 How Hormones Interact with the Nervous System and Affect Behavior • Endocrine glands: glands that secrete chemicals called hormones directly into the bloodstream • hormones: chemicals released into the bloodstream by endocrine glands • Pituitary gland: gland located in the brain that secretes human growth hormone and influences all other hormone-secreting glands (also known as the master gland)

  36. Figure 2.9 The Endocrine GlandsThe endocrine glands secrete hormones directly into the bloodstream, which carries them to organs in the body, such as the heart, pancreas, and sex organs.

  37. The Endocrine Glands LO 2.5 How Hormones Interact with the Nervous System and Affect Behavior • Pineal gland: endocrine gland located near the base of the cerebrum that secretes melatonin which help track day length and seasons • Thyroid gland: endocrine gland found in the neck that regulates metabolism • Pancreas: endocrine gland that controls the levels of sugar in the blood

  38. The Endocrine Glands LO 2.5 How Hormones Interact with the Nervous System and Affect Behavior • Gonads: the sex glands that secrete hormones that regulate sexual development and behavior as well as reproduction • ovaries: the female gonads • testes: the male gonads

  39. The Endocrine Glands LO 2.5 How Hormones Interact with the Nervous System and Affect Behavior • Adrenal glands: endocrine glands located on top of each kidney that secrete over thirty different hormones to deal with stress, regulate salt intake, and provide a secondary source of sex hormones affecting the sexual changes that occur during adolescence

  40. Looking inside the Living Brain LO 2.6 Study of the Brain and How It Works • Clinical Studies • Deep lesioning: insertion of a thin, insulated wire into the brain through which an electrical current is sent that destroys the brain cells at the tip of the wire • Electrical stimulation of the brain (ESB): milder electrical current that causes neurons to react as if they had received a message • Human brain damage

  41. Looking inside the Living Brain LO 2.6 Study of the Brain and How It Works • Electroencephalograph (EEG): machine designed to record the brain wave patterns produced by electrical activity of the surface of the brain • Peeking inside the brain

  42. Mapping Structure LO 2.6 Study of the Brain and How It Works • Computed tomography (CT): brain-imaging method using computer-controlled X-rays of the brain • Magnetic resonance imaging (MRI): brain-imaging method using radio waves and magnetic fields of the body to produce detailed images of the brain

  43. Mapping Structure LO 2.6 Study of the Brain and How It Works • Mapping Function • Positron emission tomography (PET): brain-imaging method in which a radioactive sugar is injected into the subject and a computer compiles a color-coded image of the activity of the brain, with lighter colors indicating more activity

  44. Mapping Structure LO 2.6 Study of the Brain and How It Works • Mapping Function • Functional MRI (fMRI): a computer makes a sort of “movie” of changes in the activity of the brain using images from different time periods • Electroencephalogram (EEG): records electric activity of the brain below specific areas of the skull

  45. Mapping Structure LO 2.6 Study of the Brain and How It Works • Mapping Function • Single photon emission computed tomography(SPECT); similar to PET, but uses different radioactive tracers • Measures blood brain flow

  46. The Brain Stem LO 2.7 Structures and Functions of the Bottom Part of Brain • Medulla: the first large swelling at the top of the spinal cord, forming the lowest part of the brain, which is responsible for life-sustaining functions such as breathing, swallowing, and heart rate.

  47. The Brain Stem LO 2.7 Structures and Functions of the Bottom Part of Brain • Pons: the larger swelling above the medulla that connects the top of the brain to the bottom and that plays a part in sleep, dreaming, left–right body coordination, and arousal • Reticular formation (RF): an area of neurons running through the middle of the medulla and the pons and slightly beyond; responsible for selective attention

  48. The Brain Stem LO 2.7 Structures and Functions of the Bottom Part of Brain • Cerebellum: part of the lower brain located behind the pons that controls and coordinates involuntary, rapid, fine motor movement

  49. Structures under the Cortex LO 2.8 Structures that Control Emotion, Learning, Memory, and Motivation • Limbic system: a group of several brain structures located under the cortex and involved in learning, emotion, memory, and motivation • Thalamus: part of the limbic system located in the center of the brain, this structure relays sensory information from the lower part of the brain to the proper areas of the cortex and processes some sensory information before sending it to its proper area

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